Liquid crystal display devices are currently used in a variety of applications. In a general liquid crystal display device, one pixel is comprised of three subpixels respectively representing red, green and blue, which are the three primary colors of light, thereby conducting a display operation in colors.
The general liquid crystal display device, however, can reproduce colors that fall within only a narrow range (which is usually called a “color reproduction range”), which is a problem. Thus, to broaden the color reproduction range of liquid crystal display devices, a technique for increasing the number of primary colors for use to perform a display operation has recently been proposed.
For example, Patent Document No. 1 discloses a liquid crystal display device 800 in which one pixel P is made up of four subpixels that include not only red, green and blue subpixels R, G and B representing the colors red, green and blue, respectively, but also a yellow subpixel Y representing the color yellow as shown in FIG. 13. That liquid crystal display device 800 performs a display operation in colors by mixing together the four primary colors red, green, blue and yellow that are represented by those four subpixels R, G, B and Y.
By performing a display operation using four or more primary colors, the color reproduction range can be broadened compared to the known liquid crystal display device that uses only the three primary colors for display purposes. Such a liquid crystal display device that conducts a display operation using four or more primary colors will be referred to herein as a “multi-primary-color liquid crystal display device”. And a liquid crystal display device that conducts a display operation using the three primary colors will be referred to herein as a “three-primary-color liquid crystal display device”.
On the other hand, Patent Document No. 2 discloses a liquid crystal display device 900 in which one pixel P is made up of four subpixels that include not only red, green and blue subpixels R, G and B but also a white subpixel W representing the color white as shown in FIG. 14. As the subpixel added is a white subpixel W, that liquid crystal display device 900 cannot broaden the color reproduction range but can still increase the display luminance.
However, if the number of subpixels that form each pixel P is increased from three to four as in the liquid crystal display devices 800 and 900 shown in FIGS. 13 and 14, the number of signal lines to provide also needs to be increased 4/3 times. As pointed out in Patent Document No. 3, such an increase in the number of signal lines to provide would in turn increase the size of the frame area or the number of ICs (which are driver ICs to be arranged on a flexible substrate) for use in a COF (chip on film) mounting process. As a result, either the overall external size or manufacturing cost of the liquid crystal display device would increase.
Thus, to overcome these problems, Patent Document No. 3 discloses a liquid crystal display device 1000 in which subpixels are arranged in a different pattern from in the known ones as shown in FIG. 15. In the liquid crystal display device 1000, each pixel P is defined by red, green, blue and white subpixels R, G, B and W.
In the liquid crystal display devices 800 and 900 shown in FIGS. 13 and 14, the plurality of subpixels that form a single pixel P are arranged in the row direction (i.e., arranged in a row). On the other hand, in the liquid crystal display device 1000, the plurality of subpixels that form a single pixel P are arranged in the column direction (i.e., arranged in a column) as shown in FIG. 15. That is why even though color filters in respective colors are arranged in stripes so as to run in the column direction in the liquid crystal display devices 800 and 900, the color filters in respective colors are arranged in stripes so as to run in the row direction in the liquid crystal display device 1000. In this description, the former color filter arrangement in which color filters run in the column direction will be referred to herein as a “vertical striped arrangement”, while the latter color filter arrangement in which color filters run in the row direction will be referred to herein as a “horizontal striped arrangement”.
By adopting such a horizontal striped arrangement, the number of signal lines to provide can be reduced significantly compared to a situation where the vertical striped arrangement is adopted. For example, supposing the number of pixels is constant, the number of signal lines to provide for the liquid crystal display device 1000 shown in FIG. 15 can be reduced to a quarter compared to the liquid crystal display devices 800 and 900 shown in FIGS. 13 and 14. If the number of signal lines to provide is reduced significantly, then there is no need to increase the size of the frame area or the number of ICs for use in the COF mounting process. As a result, it is possible to prevent the overall external size or manufacturing cost of a liquid crystal display device from increasing.